In application Ser. No. 739,886, filed Nov. 8, 1976, the inventor herein disclosed compounds useful as anti-juvenile hormones which were chromenes corresponding to the general formula: ##STR8## wherein:
R and R.sub.1 are H, lower alkyl, straight or branch chain, of about 1 to 4 carbon atoms, lower alkoxy, straight or branch chain, of about 1 to 3 carbon atoms, Cl, Br or F;
R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are H, lower alkyl, straight or branch chain, of 1 to 6 carbon atoms, lower alkoxy, straight or branch chain, of 1 to 6 carbon atoms, OH, --OCH.sub.2 OCH.sub.3, --OC.sub.2 H.sub.4 OC.sub.2 H.sub.5, --CO--OCH.sub.3, --CO--OCH.sub.2 CH.sub.3, ##STR9## Cl, Br, F, --SCH.sub.3, --SCH.sub.2 CH.sub.3, --SCH.sub.2 CH.sub.2 CH.sub.3, --NO.sub.2, dimethylamino, diethylamino, or the structure wherein R.sub.2 and R.sub.3, or R.sub.3 and R.sub.4, or R.sub.4 and R.sub.5 are joined with a --OCH.sub.2 O-- (methylenedioxy) group, or --OCH.sub.2 CH.sub.2 --(ethylenedioxy) group and
Y is O, S or NH.
Of the various chemical compounds, other than such anti-juvenile hormones, which have been employed in the prior art as insecticides for controlling insects, many of such prior art compounds have also been found to be harmful to humans and other animal life. In addition, many species of insect pests have developed a resistance and even immunity to available insecticides.
Alternative prior art methods for controlling insects have included the use of hormones, which interfere with the development of insects. Although such hormones have the advantage of apparently being harmless to other animals, their use is generally limited to application relatively late in the insect life cycle, after the insect has already produced its undesirable pest effect.
The endocrine systems of insects secrete a certain hormone known as juvenile hormone which functions to control the biological activities of metamorphosis, reproduction, diapause and sec attractant production. In particular, juvenile hormone functions initially to maintain the young developing insect in an immature condition until it has developed to the point where it is ready to molt to the adult form. When maturation of the insect begins, the body ceases to secrete juvenile hormone until after the insect has passed into the adult form, at which time secretion of juvenile hormone recommences in order to promote the development of the sex organs.
The forms in which juvenile hormone are known to occur in nature are discussed, for example, in the following publications: Trautmann et al., Z. Naturforsch, 29C 161-168 (1974); Judy et al., Proc. Nat. Acad. Sci. USA, 70, 1509-1513 (1973); Roller et al., Angew. Chem. Int. Ed. Eng., 6, 179-180 (1967); Meyer et al., Proc. Nat. Acad. Sci. USA, 60, 853-860 (1968); Judy et al., Life Sci., 13, 1511-1516 (1973); Jennings et al., Life Sci., 16, 1033-1040 (1975); and Judy et al., Life Sci., 16, 1059-1066 (1975).